Skywatchers, take note: This week is your best opportunity of the year to see the planet Mercury as a "morning star."

Of the five planets known since antiquity, Mercury is by far the most rarely seen by the average person. In fact many serious astronomers missed out on the planet Mercury, including the famous German astronomer, Johannes Kepler.

The reason why Mercury is so rarely spotted is not that it isn't bright: In fact, it's generally one of the brightest objects in the sky. Mercury's problem is that in never strays very far from the sun, so its bright light is always dimmed by the greater glory of our nearest star. [Gorgeous Mercury Photos From Messenger Mission]

Our best chances of seeing Mercury are during the periods when it is farthest from the sun, called greatest elongations. Because of the inclination of the ecliptic, the path the sun and planets take through the sky, not all elongations are equal. Only twice a year is Mercury's elongation favorable, once in the evening and once in the morning.

This week is the best morning elongation of 2011 for observers in the Northern Hemisphere. The best evening elongation this year was in late March. Good elongations in one hemisphere are usually bad ones for the other hemisphere, so the best elongations in the south this year are May 7 (morning) and Nov. 14 (evening).

The best way to spot Mercury this week is to find an observing location with a low eastern horizon. Start looking at least half an hour before sunrise; it may help to sweep the horizon with binoculars.

The predawn sky is ablaze with bright, first magnitude stars: Sirius, Procyon, Betelgeuse and Rigel in Orion, Castor and Pollux in Gemini, and Regulus in Leo. Mars is now shining brightly right alongside Castor and Pollux, forming a distinctive triangle which can guide you straight to Mercury below them.

If you point a telescope at Mercury, you won't see very much, because Mercury is very small and close to the horizon, where the air is most turbulent, causing light to blur. Follow Mercury with your telescope as it gets higher in the sky, and the image will gradually improve, as Mercury rises above the turbulence. This is the secret for getting the best telescopic views of Mercury: find it in twilight, then follow it as it rises.

Science editor Alan Boyle's blog: "Astronaut Abby" is at the controls of a social-media machine that is launching the 15-year-old from Minnesota to Kazakhstan this month for the liftoff of the International Space Station's next crew.

Over the next week, the relationship of these bright objects will change. Because of the Earth's movement around the sun, the stars will all shift upward and to the right, while the two planets will move downward and to the left.

Notice that this puts Mercury and Regulus on a "collision course." Next Friday morning, Sept. 9, there will be a conjunction between Mercury and Regulus. These two objects will then fit together comfortably in the eyepiece of most small telescopes.

Southern stargazing

Stars, galaxies and nebulas dot the skies over the European Southern Observatory's La Silla Paranal Observatory in Chile, in a picture released on Jan. 7. This image also shows three of the four movable units that feed light into the Very Large Telescope Interferometer, the world's most advanced optical instrument. Combining to form one larger telescope, they are greater than the sum of their parts: They reveal details that would otherwise be visible only through a telescope as large as the distance between them.
(Y. Beletsky / ESO)
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A balloon's view

Cameras captured the Grandville High School RoboDawgs' balloon floating through Earth's upper atmosphere during its ascent on Dec. 28, 2013. The Grandville RoboDawgs’ first winter balloon launch reached an estimated altitude of 130,000 feet, or about 25 miles, according to coaches Mike Evele and Doug Hepfer. It skyrocketed past the team’s previous 100,000-feet record set in June. The RoboDawgs started with just one robotics team in 1998, but they've grown to support more than 30 teams at public schools in Grandville, Mich.
(Kyle Moroney / AP)
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Spacemen at work

Russian cosmonauts Oleg Kotov, right, and Sergey Ryazanskiy perform maintenance on the International Space Station on Jan. 27. During the six-hour, eight-minute spacewalk, Kotov and Ryazanskiy completed the installation of a pair of high-fidelity cameras that experienced connectivity issues during a Dec. 27 spacewalk. The cosmonauts also retrieved scientific gear outside the station's Russian segment.
(NASA)
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Special delivery

The International Space Station's Canadian-built robotic arm moves toward Orbital Sciences Corp.'s Cygnus autonomous cargo craft as it approaches the station for a Jan. 12 delivery. The mountains below are the southwestern Alps.
(NASA)
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Accidental art

A piece of art? A time-lapse photo? A flickering light show? At first glance, this image looks nothing like the images we're used to seeing from the Hubble Space Telescope. But it's a genuine Hubble frame that was released on Jan. 27. Hubble's team suspects that the telescope's Fine Guidance System locked onto a bad guide star, potentially a double star or binary. This caused an error in the tracking system, resulting in a remarkable picture of brightly colored stellar streaks. The prominent red streaks are from stars in the globular cluster NGC 288.
(NASA / ESA)
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Supersonic test flight

A camera looking back over Virgin Galactic's SpaceShipTwo's fuselage shows the rocket burn with a Mojave Desert vista in the background during a test flight of the rocket plane on Jan. 10. Cameras were mounted on the exterior of SpaceShipTwo as well as its carrier airplane, WhiteKnightTwo, to monitor the rocket engine's performance. The test was aimed at setting the stage for honest-to-goodness flights into outer space later this year, and eventual commercial space tours.

Red lagoon

The VLT Survey Telescope at the European Southern Observatory's Paranal Observatory in Chile captured this richly detailed new image of the Lagoon Nebula, released on Jan. 22. This giant cloud of gas and dust is creating intensely bright young stars, and is home to young stellar clusters. This image is a tiny part of just one of 11 public surveys of the sky now in progress using ESO telescopes.
(ESO/VPHAS team)
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Fire on the mountain

This image provided by NASA shows a satellite view of smoke from the Colby Fire, taken by the Multi-angle Imaging SpectroRadiometer aboard NASA's Terra spacecraft as it passed over Southern California on Jan. 16. The fire burned more than 1,863 acres and forced the evacuation of 3,700 people.
(NASA via AP)
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Where stars are born

An image captured by NASA's Spitzer Space Telescope shows the Orion Nebula, an immense stellar nursery some 1,500 light-years away. This false-color infrared view, released on Jan. 15, spans about 40 light-years across the region. The brightest portion of the nebula is centered on Orion's young, massive, hot stars, known as the Trapezium Cluster. But Spitzer also can detect stars still in the process of formation, seen here in red hues.
(NASA / JPL-Caltech)
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A long, long time ago...

This long-exposure picture from the Hubble Space Telescope, released Jan. 8, is the deepest image ever made of any cluster of galaxies. The cluster known as Abell 2744 appears in the foreground. It contains several hundred galaxies as they looked 3.5 billion years ago. Abell 2744 acts as a gravitational lens to warp space, brightening and magnifying images of nearly 3,000 distant background galaxies. The more distant galaxies appear as they did more than 12 billion years ago, not long after the Big Bang.
(NASA / NASA via AFP - Getty Images)
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Frosty halo

Sun dogs are bright spots that appear in the sky around the sun when light is refracted through ice crystals in the atmosphere. These sun dogs appeared on Jan. 5 amid brutally cold temperatures along Highway 83, north of Bismarck, N.D. The temperature was about 22 degrees below zero Fahrenheit, with a 50-below-zero wind chill.